Yeah i get those stains also, not hard to clean at all but wonder where they come from seem oily or grimmy, not just a water stain

 

I have those sticky substance too!

IMHO, this could be the anti-rust substance that coats the interior, prevents rust from inside out.

 

Again, do other body styles have this problem? I don't think so, or else I would have seen it. Disagree? :'(

Secondly, the point of starting of the 'stains' seems aligned with the front of the rubber (?) weatherstip on the underside of the door. I noted that it isn't a single wrap-around structure. Could there be some material comming from there and mixing with road dirt (+brake dust) to make it stickier? Like the rust-proofer mentioned above? Is it dark from tire dust and only stains with a certain tire? (I have Portenzas RF.) It may the tires because the stain is on the rear door as well and further away from the front wheel but less intense.

Does everyone have this problem but not find it important enough to comment here? The stains are there the many times I have washed the car and have not slowed down. Wax only makes it easier to clean. It doesn't seem to prevent it. Is it weather related (besides showing up after rain), meaning regional ? I am in SE US.

I am not satisfied with the solution of just puting wax on the paint and cleaning after each rain. I should not have to do such maintenance with such an expensive car. I am glad to clean and wax to protect the investment and show off the car, but I never saw such stains before on any other car I owned. Brake dust is more tolerable to me because it (probably) results from a formulation that provides the best performance.

 

OK, it looks like nobody knows about these stains.
I took pictures of the stains that developed after only 1 day of rain. This one is from the rear door. I have had it much worse and it was difficult to remove them at first.

 

The stains show up in the same place every time. Here is the one from the front door on the passenger side. (I get 4 stain trails every time.)
Any answers to the questions I raised above?

 

I have the same stains but mine are more wide. Where yours is about 1 cm wide mine are 5cms wide and look the same. I have them at the A pillar and B pillar at the underside of the car in the same spot you have. I think it is the grease they use on the doorhinges that comes of when it's raining. I've had it with a Seat before and it went away after a while because the grease was going of the doorhinges.

 

I get them too but they clean up pretty easilly with regular washing. Sometimes I'll use Zymol Field Glaze if I don't have time to wash the whole car.

 

Ah, those stains. That is reminiscent of the stains on my '97 540-6. At that time, the dealer told me that this was a lubricant that BMW used on the doors and that it would go away in time. Those stains were most prominent below the front door hinges. They didn't tell me that time for the stains to go away would be years and years. <_< I think I removed them with bug and tar spray and waxed over every time.

So far, I have been spared those stains with the E60. But since it is garaged a lot, most of the water it has seen has been out of a hose.

 

530e60nl and jdn hit the problem on the head. It is exactly from the grease used for the door hinges. It is annoying, but a needed evil to keep the hinges in good working order. The problem with it is that some of it flows down when wet. When it stops flowing down, it probably is time to get the hinges greased again, unfortunately. Maybe someday they'll make a lubricant that won't move from where it is put.

 

Thank you. Finally the source of the problem and it is not unique to E60.
Now explain how grease and water mix? And if it is grease, then the stains could be regional-more stains where it is hot since grease will flow more.

If it is hinge grease, then a pad or plastic barrier under the hinge could cut the path of excess grease?

Wax has a chemical affinity for grease, so I don't think waxing will make cleanup easier.